Biomarker identification by proteomic analysis of vitreous humor and plasma from diabetic retinopathy patients

Abstract

Purpose : To determine potential mediators and disease progression biomarkers of diabetic retinopathy (DR) in vitreous humor and plasma samples from patients using SomaScan proteomics platform.

Methods : Vitreous humor (VH) and plasma samples were collected from DR (60 Non-proliferative Diabetic Retinopathy/NPDR, 60 Proliferative Diabetic Retinopathy/PDR) and 60 control patients undergoing vitrectomy as standard of care for underlying ophthalmological conditions. An aliquot of processed VH (homogenized with protease inhibitors) and plasma were sent to SomaLogic to be run on the SomaScan Assay (a highly multiplexed, aptamer-based proteomics assay). Differential expression analysis was run to identify protein expression between disease groups. Pathway enrichment analysis was run to identify significantly perturbed pathways in DR. We built a random forest model to identify biomarkers, predictive of disease progression.

Results : Using SomaScan proteomics platform, we measured about 5000 proteins in vitreous humor and plasma samples from three groups (control, NPDR & PDR). The most profound change was identified in PDR VH, minimal changes were seen in plasma samples, likely indicating the local pathogenesis of PDR. Many key molecules and molecular pathways such as VEGF, EPO, and inflammation implicated in DR are significantly increased in the vitreous humor of PDR patients. Besides classic pathways (hypoxia, immune response) which are involved in PDR, we also identified mTORC1 signaling, HEME metabolism, and adipogenesis. By machine learning algorithm, SCARA5, a scavenger receptor was identified as the top PDR predictive marker in plasma with Mean Decreased Gini number 4.2.

Conclusions : Our data suggest profound changes of protein expression and molecular pathways in PDR vitreous humor, indicating the involvement of local rather than systemic factors in the pathogenesis of DR. Data also suggest the involvement of inflammation and activation of microglia/macrophage in the pathogenesis of DR. Although the systemic changes related to DR are small, a few biomarker candidates were identified and planned for further investigation.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.